Air impact hammer



Nov. 8, 1955 J. F. KIMBALL 2,722,918

. AIR IMPACT HAMMER Filed March 2, 1951 32' 68 INVENTOR FIE; M

JAMES F- KIMBALL BY vnaJumjmm ATTORNEY United States Patent '0 R Iaines Kimball, Jackson, Mich. Application March 2, 1951, Serial No. 213,538 '1 Claim. Cl. 121-17 Thisinve'ntion relates 'to'air impact hammers and particularly to portable'hand typehammers which are capable ofbeinghooked'up to'a source of'coinpressed air.

It is an object of this invention to provide an air impact hammer which "is not only exceedingly effective in use 'ibll til S also constructed from relatively simpleand few movable parts, and which can be readily manufactured assembled to provide an exceptionally robust and efficient air'iinpact hammer.

It is a further objectof the invention to provide an air impact hammer which is of simple design and ;construction btitutilii'es the supplied air pressure to obtain a high pulsation effect.

Further objects and advantages of the invention, residing in the construction, arrangement and combination of parts, will appear clear from a consideration of the following description of two practical forms of the invention, by way of example, with reference to the accompanying drawings in which: i

Fig. I is a longitudinal section of one form of air hammer in accordance with the invention, with the air flow control plunger in retracted position,

Fig. II is a similar view to Fig. I (the bottom portion of the handle being broken away) showing the air flow control plunger in projected position,

Fig. III is a perspective view of the air flow control plunger, and

Fig. IV is a fragmentary longitudinal section of another form of the invention, employing a spring return action. Referring to the drawings, and first to Figs. IIII, indicates, generally, an air gun having a barrel 12 and a handle 14 carrying a control trigger 16 pivotally mounted upon the handle at 18. The trigger, through the medium of the actuator rod 20, controls the opening of a valve element 22, shown in the form of a ball normally urged by a spring 24 against a seat 26 to seal oti the flow of pressure air from a duct 28 in the handle to an elbow duct 30, 32 providing communication with the interior of the barrel 12 in the manner to be described.

The handle has a screwed nipple 34 by which the gun can be hooked up, by a flexible pipe line (not shown), to a source of compressed air. The spring 24, on release of pressure upon the trigger 16, serves to restore the trigger to its normal position, in which the valve 22 is held seated against the seat 26 to seal off communication between the duct 28 and the elbow duct 30, 32 as shown in the full line position of this ball valve in Figs. I and II. The open position of this valve is as indicated in dotted lines.

The barrel 12 accommodates, at its mouth end, an impact applying piston 34, through the medium of which the hammer blows are imparted to a tool, such as a riveter 36, by the impact of a plunger 38 slidably mounted in the barrel to define at one end thereof, between the plunger and the piston 34, an air chamber 40, and between the plunger and the rear end of the plunger, an air chamber 42.

The chamber 40 is sealed at its ends by the piston 34 2,722,918 ii entea Nov. .1955

and the plunger '38 :whereas the chamber 42 is sealed at one .end by the plunger 34 and, at its opposite end, bya plug 41 screwed into the screw-threaded rear end of the b r el- 'thepositions'oflFigs. I and II.

The plunger -3 8 is of stepped formation to provide a reduced end portion 48, a pair of axially spaced annular chambers and 52,-an dthree piston surfaces 54, =56;and 58. The plunger also has an axial bore extending from, and pening to,'its end adjacent the air chamber 40, and terminating within the plunger, near its oppositegend, in a transverse port ,62nvhich opens into the annular chamber 52. This bore 60 alsohas a transverse port 64 which opens into the aircharnber 40 and another axially extending bore 66, open at one end to'the annular chamber 50and at t-heoppo'site end to the air chamber 42.

In qpe ati n, w h t e {pa s shown F g- :I, a d duct26 connected t o a source of'compressed air, depression. of trig-gerjlf6 .will, actuate the rod 20 ;to open ,the Jvalve 2 2 againstthe actioniqfitsppring .24 and causethe compr'essedair gto rbeadmitted to .the aircham'ber 42 via the ann a chambe 0 an a ia du 6 At this time hamb A0 i aea njtb atmo ph e a .e amber 4.2 ,i closed to its exhaust port 46. Accordingly, the air pressure, acting against the plug 41, as indicated by the arrows in Fig. I, will react against the plunger 38 to shift the same violently to the left, as seen in Figs. I and II, and cause the reduced plunger end to impact sharply with the impact applying piston 34. In its movement thus, the piston portion 54 of the plunger 38 travels over the exhaust port 44 to close the latter whereas the piston portion 58 travels over the exhaust port 46 to open this port and place the annular chamber 52 in communication with the admission duct 32. This is the position of the parts as illustrated in Fig. II. In such position, the chamber 42 is exhausted as the compressed air supply is delivered to the now sealed chamber 40 via the duct 32, annular chamber 52, port 62, axial duct 60 and port 64 as indicated by the arrows in Fig. II. This causes a reaction of pressure against the plunger to force same to the right, back to the position seen in Fig. I. This cycle of operations will persist at rapid rate while the trigger 16 is held depressed and will produce a rapid pulsation of the tool 36.

In Fig. IV the hammer is indicated generally at 10' with its barrel at 12', handle at 14 and trigger control at 16'. The handle construction of this embodiment is similar to that of the previously described embodiment with the valve 22, inlet port 26 and elbow duct, of which latter there is shown only the portion 32 in Fig. IV, opening, in the position shown, into an annular chamber 63 in a plunger and having a port 72 opening into an air chamber 74 at the rear end of this plunger and with respect to which chamber the barrel provides an atmosphere exhaust port 76. The forward end of this plunger is reduced but solid, as indicated at 78 and defines one end of an air chamber 40', having an exhaust port 44 and the opposite end of which is defined by the impact applying piston 34' sealing off the mouth end of the barrel 12'.

The plunger end portion 78 receives one end of a return coil spring 80, the opposite end of which seats in a recess 82 on the inside face of the impact piston 34'.

In this embodiment of the invention the admission of compressed air into the chamber 74 in the condition of the parts as shown will cause the plunger 70 to be moved to the left against the action of the spring 80 and deliver an impact force against the piston 34' and hence the riveter 26', with energy being stored up in the compressed spring. This will alternate rapidly between the forcing of the plunger to the left, as seen in Fig. IV and the returning of the plunger to the right by the release of the compressed spring when the exhaust port 76 is uncovered at the end of the forward movement of the plunger.

It will be appreciated, therefore, that I have provided an exceedingly'simple and compact construction of air hammer which has few moving parts and can be readily manufactured and assembled.

Having thus described my invention, what I claim is new and desire to cover by Letters Patent is:

An air impact hammer comprising a main body structure defining a barrel and a handle, an air inlet passage defined in said handle and opening through the wall of said barrel into the interior thereof between the ends of said barrel, a manually actuated throttle valve in said inlet passage, an impact applying member located in one end of said barrel, an air control and impact plunger located in said barrel for longitudinal reciprocation intermediate the ends thereof, means closing the other end of said barrel, opposite ends of said plunger being shaped to provide chambers at opposite ends of said plunger, said chambers being defined in part by said plunger ends and the interior Wall of said barrel, longitudinally spaced annular grooves defined in the outer surface of said plunger for alternate register with said air inlet upon reciprocation of said plunger, a longitudinal bore in said plunger connecting with one of said grooves and opening through one end of said plunger into one of said chambers, a second longitudinal bore in said plunger connecting with the other of said grooves and opening through the other end of said plunger into the other of said chambers, longitudinally spaced radially extending exhaust ports defined in the wall of said barrel and opening directly into said chambers, said plunger having a portion overlapping one of said exhaust ports to close the same with said plunger at the end of its reciprocation in said first chamber, another portion of said plunger closing said other exhaust port with said plunger at the end of its reciprocation in said other chamber, said last exhaust port registering with one of said grooves to exhaust air from said first chamber through the interior of said plunger with the other of said grooves in register with said inlet port for admitting air to said second chamber.

References Cited in the file of this patent UNITED STATES PATENTS 542,498 Rinsche July 9, 1895 558,652 Meyer Apr. 21, 1896 906,240 Kreger Dec. 8, 1908 1,122,630 Peck Dec. 29, 1914 1,174,869 Ioecken Mar. 7, 1916 1,175,621 Ekberg Mar. 14, 1916 1,440,082 lnslee Dec. 26, 1922 1,486,486 Gates Mar. 11, 1924 1,535,659 Fog Apr. 28, 1925 2,413,542 Butts Dec. 31, 1946 2,585,975 Terry Feb. 19, 1952 FOREIGN PATENTS 54,934 Germany Jan. 12, 1891 

